add password change

move to dictionary instead of expando
   https://github.com/pgina/pgina/commit/efb04028bc69b2d197097633647e4aedd9c00988
Fix a memory leak in credential initialize. Do not dup pre-set value if field is dynamic (and is going to then also dup a value)
   https://github.com/pgina/pgina/commit/c3ca64781c750f6ad81491af99ffc8209934e014
Fix issue #199 - Set field string to NULL after clearing it
   https://github.com/pgina/pgina/commit/4c402dcafb52dd6dd367b9e6eec8a6ffeca80a03
Fix for issue #191 - No more expandos in RPC
   https://github.com/pgina/pgina/commit/6ad6345fa8a715ef1b63df7f644e7a977ed3aea0
Make overloads use IDictionary
   https://github.com/pgina/pgina/commit/1bb2e2ac48f3d3350704c795137ca5e9c7e265f5
Add initial cred-prov support for change password scenario
   https://github.com/pgina/pgina/commit/69eb9f33f3fb0388d1183ab63993631678232a38
Add password change pipe message
   https://github.com/pgina/pgina/commit/0d9dd9e1a5ce2f065e4174bbb9f0eff42539d482
Begin change password support in config
   https://github.com/pgina/pgina/commit/f90bf05cd48e447739232bd00890b124acfee733
Configuration support for change password
   https://github.com/pgina/pgina/commit/5d5bb861ad866a491233935f77fd370722f7578f
Change password support
   https://github.com/pgina/pgina/commit/4d22874be165187e5c2e86b5e756f38336041120
Bug fix and improved messaging for change password
   https://github.com/pgina/pgina/commit/db4ebd74991b6949c509eebb27ba16582aeac2d6